Various types of devices for ventilating toilet bowls have been proposed and can be categorized into several groups according to their construction and mode of operation.
A number of devices exist where the ventilation system is attached to the seat, is a part of the seat, or is built into the seat itself. Typical of these are: U.S. Pat. No. 4,620,329, which discloses a toilet having an internal channel in the seat for the conveyance of air through hollow hinge mechanisms; and U.S. Pat. No. 4,094,023, which discloses a toilet seat having a perforated suction tube attached on the underside of an exhaust tube running down that extends into the bowl. These ventilation system can cause a sanitary problem due to the presence of baffles, channels and openings along the underside of the seat and/or tubing located in the bowl which present a breeding ground for bacteria.
Other devices exist in which the ventilation system is formed in the toilet bowl independent of the water closet, and these require construction of the bowl itself and in U.S. Pat. Nos. 3,938,201 and 4,222,129. Once again, unsanitary conditions are present.
Still other systems exist which are attached to the toilet bowl or hung on the side thereof such as in U.S. Pat. No. 4,317,242. These designs result in either an inconvenient or hazardous condition.
There are ventilating devices where the ventilation is achieved through the overflow pipe, such as is exhibited in U.S. Pat. Nos. 4,232,406, 4,165,544, and 3,495,282. These inventions all suffer from insufficient airflow volume to adequately ventilate the toilet.
Ventilating devices also exist that are positioned between the seat and the toilet bowl as exhibited in U.S. Pat. Nos. 3,069,696 and 4,402,091. These devices suffer from safety and sanitation problems due to the additional tubing and vents.
A few designs provide a ventilating system by adding a vent adapter between the toilet bowl and the water tank, all in communication with one another, as exhibited in U.S. Pat. Nos. 2,777,137, 3,230,552, and U.S. Pat. No. 4,494,255. because the vent adapter is not an integral part of either the toilet bowl or the water closet, the device itself, as well as the crevices formed by the planes of connection, once again pose sanitation hazards and/or air flow constraints. Also, this exposed vent adapter is unsightly.
U.S. Pat. No. 2,351,560 uses a vent adapter positioned in the water inlet connecting the closet to the bowl, but requires a major structural change in the configuration of the water closet to house a suction fan and motor assembly, and the motor wiring creates an electrical hazard.
In general, the above, ventilation systems have one or more of the following problems: inadequate sanitation, unsightly appearance, physical obstruction, electrical shock hazard, lack of plumbing code compliance and/or expense. Also, none of the above systems are suitable for use with a recreational vehicle or boat toilet.